Electrophotography is a useful process for printing images on a receiver (or “imaging substrate”), such as a piece or sheet of paper or another planar medium, glass, fabric, metal, or other objects as will be described below. In this process, an electrostatic latent image is formed on a photoreceptor by uniformly charging the photoreceptor and then discharging selected areas of the uniform charge to yield an electrostatic charge pattern corresponding to the desired image (a “latent image”).
After the latent image is formed, charged toner particles are brought into the vicinity of the photoreceptor and are attracted to the latent image to develop the latent image into a visible image. Note that the visible image may not be visible to the naked eye depending on the composition of the toner particles (e.g. clear toner).
After the latent image is developed into a visible image on the photoreceptor, a suitable receiver is brought into juxtaposition with the visible image. A suitable electric field is applied to transfer the toner particles of the visible image to the receiver to form the desired print image on the receiver. The imaging process is typically repeated many times with reusable photoreceptors.
The receiver is then removed from its operative association with the photoreceptor and subjected to heat or pressure to permanently fix (“fuse”) the print image to the receiver. Plural print images, e.g. of separations of different colors, are overlaid on one receiver before fusing to form a multi-color print image on the receiver.
Dry toner is a powder and is supplied from supply bottles or other containers to the photoreceptor to develop the latent image into a visible image. However, toner particles can adhere to components of the printer other than the latent image on the photoreceptor. Moreover, some toner particles can remain on the photoreceptor even after transfer of the visible image to the receiver to form the print image. Toner that enters the printer but does not exit as part of a print image on a receiver is collected and discarded as waste toner.
EP 0 738 940 B1 to Hashimoto describes collecting waste toner in a waste containing box. When the waste toner box fills, it is removed and replaced with another one. One waste box is provided for all toners in the printer. In other embodiments, one waste box or bottle is provided per printing module (color channel). In these schemes, the waste toner is generally discarded. In some printers, the waste bottles themselves are also discarded. Discarding waste toner and bottles increases the total waste produced by the printer. It also adds another consumable to be ordered and stocked by the user of the printer, namely, empty bottles to receive the waste. Furthermore, the operator of the printer is required to replace waste bottles when they become full. This can happen at the same time as the emptying of toner supply bottles, or at different times; in the latter case, the operator's workload to service the printer is increased.
U.S. Patent Publication No. 20090232548 by d'Entrecasteaux describes a toner bottle with a fresh-toner compartment and a waste-toner compartment. Waste toner is returned to the bottle from the marking engine. Although this scheme does not require separate toner and waste bottles, when the bottle fills with waste it is either discarded, increasing waste, or returned for recycling, increasing handling effort.